The Australian Christian Lobby has said that Prime Minister Julia Gillard's decision to withdraw from speaking at an ACL conference because she took offense to a comment on homosexuality made by the group's leader will be seen as an "abandonment of the Christian constituency."

ACL's leader Jim Wallace compared the negative effects of smoking to same-sex marriage during a debate on marriage equality at the University of Tasmania on Wednesday, AFP shared.

"I think we're going to owe smokers a big apology when the homosexual community's own statistics for its health – which it presents when it wants more money for health – are that it has higher rates of drug-taking, of suicide, it has the life of a male reduced by up to 20 years," Wallace told the audience.

"The life of smokers is reduced by something like seven to 10 years and yet we tell all our kids at school they shouldn't smoke," he added.

In response to these remarks, Gillard, who is an atheist, said on Thursday that she is canceling her plans to speak at the ACL conference in Canberra on Oct. 5 and 6, deeming that Wallace's comparison had been too "offensive."

"To compare the health effects of smoking cigarettes with the many struggles gay and lesbian Australians endure in contemporary society is heartless and wrong," Gillard said in a statement on Thursday. "In light of this, I believe my attendance at the conference would be inappropriate."

The ACL leader has defended his comments, however, and said that Gillard's decision to step away from the conference breaks her promise to the people.

"Many people will see this as the abandonment of the Christian constituency," Wallace said.

"I think homosexual people are well aware of the consequences of their lifestyle," he added about his previous comments.

He noted that despite his warning against the homosexual lifestyle, he counts many gay people among his friends. "The ones I know respect my stance and I respect their circumstances," he said.

The topic of same-sex marriage remains a controversial one in Australia, and a number of churches have opposed recent plans by lawmakers to try and legalize the practice.

Australia's Tasmanian Premier Lara Giddings, who is pushing for a change in the traditional definition of marriage, has said: "There is nothing that I have received in my legal advice that would preclude the state government from pursuing this matter and legalizing marriage here in Tasmania."

Both the Australian Christian Lobby and NSW Council of Churches, a representative body of evangelical Christian denominations, have come out in defense of preserving traditional marriage.

The Rev. David Jones, the leader of the Presbyterian Church of Australia commented: "Plain and simply, Christians oppose same-sex marriage because the Bible, the word of the God who created male and female and also created marriage, clearly and distinctly says that marriage is between one man and one woman – which means not between two men or two women."